The present invention relates to nanoscale electromechanical devices and their use in medical therapy. More particularly, the present invention relates to an energy-releasing carbon nanotube transponder that can be fabricated from a plurality of carbon nanotubes optionally attached to at least one biomolecule ligand and connected to a nanocapacitor. Such an energy-releasing carbon nanotube transponder can be placed in cellular tissue to treat multiple afflictions.
The term “patient” is usually understood as any person who receives medical attention, care, or treatment. However, many afflictions found in human patients can also be found in s for example cancer. The patients of veterinarians are animals. Therefore it should be understood that the invention described in this application can be used to treat humans and animals. Moreover, in this application the term “animal” includes any non-human multicellular, eukaryotic organisms such as for example fish, birds, insects, reptiles, and non-human mammals.
The term “tissue” usually describes an ensemble of cells, not necessarily identical, that together carry out a specific function. For example, organs are formed by the functional grouping together of multiple tissues. However, this invention encompasses the field of nanotechnology, therefore the invention described in this application is so small that it can be used to treat a single cellular entity, for example a single neuron or a single cancer cell, it should be understood, that when the term “tissue” is used in this application, it is meant one or more cells as appropriate for treatment. Moreover, in this application, the term “cell” includes any “cellular entity” and it should not be limited to human and animal cells, for example, the term “cell” in this application encompasses bacterial or even viral entities. For example, cancers are sometimes of viral or bacterial origins, therefore the treatment of cancer, as described in this application, can also include the destruction of the bacterial and/or the viral entities that trigger or promote cancer.
In this application, the term “treatment” should not be limited to a synonym for therapy used to remedy a health problem, but should also be broadened to mean a process of modifying or altering one or more cells.
Cancer is presently one of the most difficult fatal conditions to treat. President Nixon declared “war” on cancer back in 1971, and research for cancer treatments has remained at a high level since then. Cancer is caused by the growth of malignant cells in a patient. Conventional treatments for cancer seek to kill or inhibit the growth of cancer cells, but also kill or inhibit the growth of healthy cells as well. The search for a balance between treating cancer and not killing the patient can often result in unsuccessful cancer treatment. Therefore, there is a need for cancer treatments that better target malignant cells without damaging healthy cells.
In brain cancer, infiltrative primary high-grade neoplastic cells in the central nervous system (CNS) are often resistant to conventional chemotherapeutic and radiation therapies. Chemotherapy and radiation administered both inside the CNS and outside the blood brain barrier often cannot reach densely packed malignant cells even following resective debulking. Moreover, conventional chemotherapeutic agents can have limited efficacy due to factors ranging from systemic toxicity, to impaired drug transport secondary to decreased vascularization of the neoplasm core and P-glycoprotein-mediated drug efflux. These limitations of conventional therapies have inspired investigational nanotechnology approaches to therapy.
Epilepsy is one of the world's oldest recognized conditions. The World Health Organization (WHO) estimates that about 50 million people worldwide suffer from epilepsy. See WHO Fact Sheet No. 999 (January 2009). Epilepsy is caused by sudden, usually brief, electrical discharges in the brain. The symptoms can range from a brief loss of attention to prolonged and severe convulsions.
Epilepsy can be thought of as being like an electrical circuit that has been disturbed and has become unstable. Many patients manage their symptoms with drugs that inhibit the onset of epileptic seizures. However, many individuals are affected by medically intractable epilepsy where surgical options are minimal or non-existent. To address these issues novel treatment approaches are being developed: The delivery of treatment stimulation contingent on detection of the ictal onset (e.g. seizure) at the epileptic source is the next generation of implantable technologies directed toward optimizing containment of epileptic brain circuits. Such technologies are crucial in individuals with medically intractable epilepsy where surgical options are minimal or non-existent. Results emerging from the Food and Drug Administration (FDA)-sponsored investigational neurostimulation trials are promising. However, nearly all patients enrolled in these studies continue to experience breakthrough seizures. Relatively bulky intracranial electrodes are utilized in these studies while the number of electrodes that can be implanted is limited by their size. Moreover, the implantation of a multiplicity of bulky electrode may result in brain tissue damage. Epileptic networks can be complex and may extend well beyond implanted bulky intracranial electrodes. To optimize stimulation of brain tissue without using bulky electrodes, a multiplicity of nanodevices can be utilized to target specific brain cells while minimizing potential brain damage.
The energy-releasing carbon nanotube transponder described in this application has significant implications outside of epilepsy. Such an energy-releasing carbon nanotube transponder can also be used to investigate the brain's ability to record and replay the neural code involved in learning and memory, as well as targeting, labeling and ablating infiltrative high-grade neoplastic, cancer cells. It can also be used, for example, to treat heart afflictions such as acute myocardial ischemia or ventricular arrhythmias.
The normal electrical conduction of the heart allows for electrical propagation to be transmitted from the Sinus Node through both atria and forward to the atrioventricular node (AV). The AV node is part of an electrical control system of the heart that co-ordinates heart rate. It electrically connects atrial and ventricular chambers. Briefly, a heart beat is normally initiated at the level of the sinus node i.e. the electric impulse-generating (pacemaker) tissue located in the right atrium of the heart, and thus the generator of normal sinus rhythm. Normal sinus rhythm is the rhythm of a healthy normal heart, where the sinus node triggers the cardiac activation. When the heart's sinus node is defective, the heart's rhythms become abnormal—either too fast, too slow, or a combination. Abnormal heart's rhythms might result in a decreased transport of oxygen to the cardiac muscle, causing lack of oxygen in the heart muscle. This lack of oxygen in the heart muscle is called a myocardial ischemia. If the oxygen transport is terminated in a certain area, for example due to ischemia, the heart muscle dies in that region. This is called an infarction.
Ventricular arrhythmias is also caused by an abnormal electrical conduction of the heart. Ventricular arrhythmias is defined as abnormal rapid heart rhythms (arrhythmias) that originate in the lower chambers of the heart (the ventricles). Ventricular arrhythmias include ventricular tachycardia and ventricular fibrillation. Both are life threatening arrhythmias. In ventricular arrhythmias, ventricular activation does not originate from the atrioventricular node and/or does not proceed in the ventricles in a normal way.
Both the sinus node and AV node stimulate the cardiac muscle. It is therefore essential to control electric conduction in heart patients such as, for example, in patients who suffer from acute myocardial ischemia or ventricular arrhythmias.
Implantable cardiac pacers and defibrillators are well-established devices that can revert potentially fatal arrhythmias back to a normal sinus rhythm by electrical stimulation of heart tissue. For example, an artificial pacemaker is a medical device which uses electrical impulses, delivered by electrodes contacting the heart muscles, to regulate the beating of the heart. Implantable artificial pacemakers are nowadays currently used in heart patients such as, for example, in patients who suffer from acute myocardial ischemia or ventricular arrhythmias. However, these artificial pacemakers are often associated with an increased risk for cardiac complications because an artificial pacemaker is an implanted bio-mechanical device that requires routine inspection and maintenance.
To optimize stimulation of cardiac tissue, nanodevices can be utilized to target specific cardiac cells. Nanosensors are emerging that can detect hydrogen ions resulting from cardiac ischemic changes. See Ramachandran et al, Design and fabrication of nanowire electrodes on a flexible substrate for detection of myocardial ischemia, Proceedings of SPIE Conferences on Nanosensors, Biosensors, and Info-Tech Sensors and Systems; The international Society for Optical Engineering (2009). However, nanosensor-triggered electrical energy-releasing devices do not currently exist that can detect anaerobic metabolism due to a lack of oxygen to trigger release of electrical energy used to defibrillate heart muscle syncytium and/or pacer cells.
Therefore, the energy-releasing nanodevice, disclosed in this application, that can be designed to target specific cells and/or release a tunable level of energy offers a great advantage over the current state-of-the-art implantable devices. Moreover, a plurality of such energy-releasing nanodevices can be delivered at close proximity of the target cells rapidly through minimally invasive methods.
Carbon nanotubes (CNT) were discovered in the early 1990s as a product of arc-evaporation synthesis of fullerenes. See Iijima, Helical microtubules of graphitic carbon, Nature 354:56-58 (1991). The name “Carbon nanotubes” is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 1/50,000th of the width of a human hair).
Carbon nanotubes have unique chemical and physical properties including ultra light weight, high mechanical strength, high electrical conductivity, and high thermal conductivity. See Sinha and Yeow, Carbon nanotubes for biomedical applications, IEEE Transactions on NanoBioscience, 30 4:180-195 (2005). These characteristics make CNT a novel nanomaterial for various biomedical applications. See Ji et al, Carbon nanotubes in cancer diagnosis and therapy. Biochimica et Biophysica Acta—Reviews on Cancer, 1806(1):29-35 (2010). Recently, research has focused on investigation of targeted delivery of functionalized carbon nanotubes to specific sites of interest. CNT can behave either as a metal or a semiconductor depending on their chiral vector. See Dresselhaus et al., Carbon Nanotubes: Synthesis, Properties and Applications, Springer, Berlin (2001). However, many of these properties can be addressed once the CNT are conjugated with different molecules.
CNT are also appropriate nanomaterials based on their unique electrical properties making them a good candidate for overcoming the limitations of convection enhanced delivery (CED) systems. Although CED systems have promising advantages due to the increased volume of drug distribution in the brain, the high pressures required for CED have a high risk of damaging the tissue. Moreover, these high pressures may result in backflows along the catheter causing poor drug distribution. See Sampson et al., Poor drug distribution as a possible explanation for the results of the PRECISE trial, Journal of Neurosurgery. 113(2):301-309 (2010).
One category of nanotube is single-walled nanotubes (SWNT). SWNT can exhibit electric properties such as high electrical conductivity that are electrically useful. SWNT are one likely candidate for miniaturizing electronics beyond the micro electromechanical scale currently used in electronics. SWNT can be integrated into complex assemblies through chemical functionalization which utilizes chemical covalent bonding between SWNT and a molecular conjugate. See Ramanathan et al., Amino-Functionalized Carbon Nanotubes for Binding to Polymers and Biological Systems. Chemistry of Materials, 17:1290-1295 (2005). An extensive ultrasonic treatment of SWNT allows for an oxidation process that leads to the opening of the tube caps and the formation of holes in the sidewalls introducing oxygen containing groups. This process uses the concept of the Stone-Wales defect that creates these functional groups on 2-3% of the sidewall area of carbon nanotubes. These groups can be chemically modified to create carbon nanotube composites. See Balasubramanian and Burghard, Chemically Functionalized Carbon Nanotubes. Small, 1:180-192 (2005). Due to the CNT size and structure they cannot be easily visualized using conventional optical and confocal microscopes. Chemical functionalization with fluorescein labels is one example of a technique for visualizing CNT, and linking associated therapeutic molecules to CNT. In effect, a type of nanocarrier drug delivery or diagnostic system can be developed.
In the prior art, investigational nanotechnology approaches are at a stage that offers a proof of principle demonstrating amelioration of cancer treatment by two emerging strategies. Namely, 1) targeted drug delivery using drugs attached to nanoparticles See Murad et al, Real-time, image-guided, convection-enhanced delivery of interleukin 13 bound to pseudomonas exotoxin, Clin Cancer Res. 12(10):3145-3151 (2006); Liu et al, Drug delivery with carbon nanotubes for in vivo cancer treatment. Cancer Res 15; 68(16):6652-6660 (2008)), and 2) targeted release of thermal energy using nanoparticles capable of emitting destructive thermal energy following absorption of external laser or electromagnetic wavelength energies. See Park et al. Cooperative nanomaterial system to sensitize, target, and treat tumors. Proc Acad Sci USA 107(3):981-986 (2010); Kam et al, Carbon nanotubes as multifunctional biological transporters and near-infrared agents for selective cancer cell destruction. Proc Natl Acad Sci USA. 102(33):11600-11605 (2005); Ganon et a, Carbon nanotube-enhanced thermal destruction of cancer cells in a noninvasive radiofrequency field. Cancer. 110(12):2654-65 (2007).
One significant way to enhance the therapeutic index of anticancer drugs is to specifically deliver these agents directly to tumor cells while being carried by a nanosized carrier. This approach can keep the anticancer drugs away from healthy cells that would otherwise be damaged by the toxic effects of these drugs. See Sapra and Allen, Ligand-targeted Liposomal Anticancer Drugs, Progress in Lipid Research 42(5):439-462 (2003). Such target-oriented delivery systems include the delivery of microspheres, nanoparticles and liposomes. See Okada et al, Gene therapy for brain tumors: cytokine gene therapy using DNA/liposome (series 3), No Shinkei Geka 22:999-1004 (1994); Kakinuma et al, Targeting chemotherapy for malignant brain tumor using thermosensitive liposome and localized hyperthermia, J Neurosurg 84:180-184 (1996).
Alternatively, instead of delivering anticancer drugs with nanoparticles, other nanoparticles are currently being tested in laboratory conditions to focus energy absorbed from external lasers to ablate tumor cells throughout the body. See Von Maltzahn et al. Computationally guided photothermal tumor therapy using long-circulating gold nanorod antennas, Cancer Res 69:3892-3900 (2009).
A fundamental element required for the successful deployment of strategies aimed at targeting particular cells is the ability to identify surface molecules expressed by, for example, tumor cells and absent in surrounding healthy cells. Therefore, neoplasm avid functional biomolecules such as monoclonal antibodies and proteins conjugated to nanoparticles is essential to a tumor cell targeting system. See Huwyler et al, By-passing of P-glycoprotein using immunoliposomes. J Drug Target. 10(1):73-9 (2002).
The expression of the interleukin-13 (IL-13) receptor is one of several targets over-expressed in 60-80% of high-grade astrocytoma cells i.e. cancer cells also known as Gliobalstoma multiforme (GBM). See Kioi et al, Convection-enhanced delivery of interleukin-13 receptor-directed cytotoxin for malignant glioma therapy. Technol Cancer Res Treat. 5(3):239-50 (2006). Human IL-13 is a cytokine protein secreted by activated T cells that elicits both pro-inflammatory and anti-inflammatory immune responses. See McKenzie et al, Interleukin 13, a T-cell-derived cytokine that regulates human monocyte and B-cell function. Proc Natl Acad Sci USA. 90(8):3735-9 (1993); Minty et al, Interleukin-13 is a new human lymphokine regulating inflammatory and immune responses. Nature. 362(6417):248-50 (1993). IL-13 has two receptor subtypes: IL-13/4R and IL-13R-alpha2. The former receptor is present in normal cells with high affinity binding shared with IL-4. The latter receptor, IL-13R-alpha2, does not bind IL-4. See Caput et al, Cloning and characterization of a specific interleukin (IL)-13 binding protein structurally related to the IL-5 receptor alpha chain. J Biol Chem. 271(28):16921-6 (1996). IL-13R-alpha2 is associated with high-grade astrocytomas and is not significantly expressed in normal tissue, with the exception of the testes. See Caput et at 1996; Debinski et al Molecular expression analysis of restrictive receptor for interleukin 13, a brain tumor-associated cancer/testis antigen. Mol Med. 6(5):440-9 (2000). Pilocytic astrocytomas, the most common astrocytic tumors in children, also over express the IL-13R-alpha2 receptor. See Kawakami et al, Analysis of interleukin-13 receptor alpha2 expression in human pediatric brain tumors. Cancer. 101(5):1036-42 (2004). In effect, the IL-13R-alpha2 receptor exists as an excellent potential target for delivering cytotoxic molecules to a variety of devastating brain tumors.
A number of attempts to use the IL-13R-alpha2 receptor of GBM as a target for brain cancer therapy have been reported both in vitro and in vivo. Some of the successful modalities attempted include, IL-13-based cytotoxins (See Nash et al, Molecular targeting of malignant gliomas with novel multiply-mutated interleukin 13-based cytotoxins. Crit Rev Oncol Hematol. 39(1-2):87-98 (2001); Husain & Puri, Interleukin-13 receptor-directed cytotoxin for malignant glioma therapy: from bench to bedside. J. Neurooncol. 65(1):37-48 (2003); Kioi et al, (2006); Murad et al, (2006)), IL-13R-alpha2-targeted viruses (See Zhou et al, Engineered herpes simplex virus 1 is dependent on IL-13R-alpha2 receptor for cell entry and independent of glycoprotein D receptor interaction. Proc Natl Acad Sci USA. 99(23):15124-9 (2002)), and IL-13R-alpha2 immunotherapy (See Mintz et al Molecular targeting with recombinant cytotoxins of interleukin-13 receptor alpha2-expressing glioma. J Neurooncol. 64(1-2):117-23 (2003); Kawakami et al, Intratumor administration of interleukin-13 receptor-targeted cytotoxin induces apoptotic cell death in human malignant glioma tumor xenogratis. Mol Cancer Ther. 1(12):999-1007 (2002)).
As a nanocarrier, CNT have been utilized as excellent candidates for attaching drug molecules, and imaging markers from radiotracers (See Singh et al. Tissue biodistribution and blood clearance rates of intravenously administered carbon nanotube radiotracers. Proc Natl Acad Sci USA. 103(9):3357-62 (2006)) to colorimetric labels (See Lee et al, Carbon nanotube-based labels for highly sensitive colorimetric and aggregation-based visual detection of nucleic acids. Nanotechnol. 18(45) 455102.1-455102.9 (2007)). Although metal contaminants used to catalyze the synthesis of CNT can potentially contribute to toxicity, biocompatibility can be achieved with new CNT purification techniques. See Lu et al, Advances in bioapplications of carbon nanotubes. Adv Materials. 21:139-152 (2009); Liu et al, Drug delivery with carbon nanotubes for in vivo cancer treatment. Cancer Res. 68(16):6652-60 (2008); Schipper et al, A pilot toxicology study of single-walled carbon nanotubes in a small sample of mice. Nat Nanotechnol. 3(4):216-21 (2008); Yang et al, Long-term accumulation and low toxicity of single-walled carbon nanotubes in intravenously exposed mice. Toxicol Lett. 181(3):182-9 (2008). Moreover, neural cells have demonstrated a preference for growing on CNT scaffolding. See Lee & Parpura, Wiring neurons with carbon nanotubes. Front Neuroengineering. 29; 2:8 (2009). CNT are promising nanoscaffolds for transporting biological ligands for diagnostic and therapeutic purposes including crossing cell membranes, particularly for proteins less than 80 kDa. See Panarotto et al, Translocation of bioactive peptides across cell membranes by carbon nanotubes. Chem Commun (Camb). (1):16-7 (2004). Once a protein ligand is bound to CNT, it has been shown to remain bound under ambient conditions. See Gruner, Carbon nanotube transistors for biosensing applications. Anal Bioanal Chem. 384(2):322-35 (2006).
The conducting ability of CNT makes these carbon-rich nanostructures impressive electromagnetic energy transducers. See Khatpal et al, Polyfunctionalized single-walled carbon nanotubes as a versatile platform for cancer detection and targeted dual therapy. Intel STS Abstract (2009). The carbon atoms comprising the building blocks of CNT demonstrate a defined periodicity throughout the nanostructure. This property gives CNT the ability to efficiently transfer electrons. Therapeutically, these electronic properties of CNT along with the significant surface area of CNT can be harnessed. For example, the CNT backbone of such novel nanostructures potentially can be transported through a medium using an electromagnetic field. In addition, the semiconducting properties of CNT can potentially deliver focused energy to ablate neoplastic cells by converting radiofrequencies into heat. See Gannon et al, Carbon nanotube-enhanced thermal destruction of cancer cells in a noninvasive radiofrequency field Cancer. 110(12):12654-65 (2007).
The technologies described in the prior-art differ from the invention disclosed in this application. The invention disclosed in this invention relies on nanotechnology that can be applied to treat, for example, brain cancers, cardiovascular diseases and brain afflictions such as epilepsy.
This application describes a novel nanoparticle. It also describes the method of using it to therapeutically treat cells inside patient tissue by delivering electrical energy to those cells. The nanoparticle possesses a molecular detection system and a nanocapacitor. The nanoparticle discharges electrical energy to cells even when those cells are found deeply embedded in a patient's tissue. Self-contained nanosensors that are integrated with nanocapacitor charging capability to stimulate the microenvironment in response to local changes do not exist in the prior-art. This disclosure describes a novel nanoparticle of up to 500 nanometers in diameter since it has been shown that a nanoparticle of up to 500 nanometers in diameter is capable of crossing the blood-brain barrier in certain disease states such as epilepsy and brain cancers.
The present disclosure also relates to nanoparticles that can be made to discharge different amounts of energy. These novel nanoparticles can be concurrently introduced into one or more epileptic circuits in the brain to detect changes during seizure activity (e.g., nanomolar increases in the transmitter glutamate. A detection threshold can be used to discharge the nanocapacitor of these novel nanoparticles to deliver direct stimulation therapy to potentially stabilize the epileptic circuit. By releasing specific amounts of energy, the nanoparticles of the current disclosure can also damage or destroy disease-inducing cells, stabilize the activity of neurons or other cells such as cardiac cells. The present disclosure also relates to nanoparticles that contain a nanocapacitor that can be recharged in energy once the nanoparticles have been discharged.